Tool 4: Flowchart visual representation of relationship between planned performance and actual performance over a period. Tool 5: Histogramgraph of side-by-side vertical bars representing a frequency distribution; it reveals patterns that remain hidden in tables of numbers, sometimes it is substituted or supplemented with a Gantt chart. Tool 6: Pareto chart based on Pareto principle (a small percentage of the elements comprising a groupaccounts for the largest fraction of the value or the impact), it ranks causes from the most significant to the least significant. Tool 7: Scatter chart graph that displays the relationship between two variables; the variable to be predicted (dependent variable) is plotted on the vertical ('Y') axis, and the variable used to make the prediction (independent variable) plotted on the horizontal ('X') axis.